Contents

Description

Aircraft Ground De/Anti Icing Holdover Time (HOT) tables, approved by the SAE G-12 Committee, are issued each year prior to the northern winter season.

These are then reviewed by AEA, FAA, and TC (Transport Canada) who are the main practical sources of HOT information and each issues their own version of the HOT Tables and associated support publications independently of each other and SAE. The generic changes from one season to the next are usually relatively few. However, in recent years, issues with residues from thickened fluids have been the main driver for the appearance of product-specific HOT tables, which are increasingly used by operators.

Other "official" sources sometimes publish HOT which are then left as "current" when they cease to be the latest versions. The effect of such out of date information being still accessible has resulted in many Operations Manuals being out of date on this critical safety subject.

In recent years, several companies have been developing systems that measure precipitation rate in real-time. These systems, referred to as liquid water equivalent systems (LWES), can be used by check-time determination systems (CTDS) and holdover time determination systems (HOTDS) to calculate more precise holdover times than can be obtained from the HOT Tables. They do this by using the weather data they collect as the input to the underlying assumptions employed in calculating the times in the HOT Tables.